New hydrophobic membranes for contactor processes — Applications to isothermal concentration of solutions Original Research Article

The application of ceramic tubular membranes on a process of extraction by gas (EG) is presented. For this purpose hydrophobic tubular membranes were made by a deposition of a thin film of a lipid compound on ceramic macroporous supports with a range of mean pore size between 0.2 and 2.0×10−6 m. The EG process is based on the concentration of an aqueous solution by vapour transfer through the hydrophobic membrane macroporosity. The aqueous solution flows on the shell side, and the gradient necessary for transfer is created by a continuous flux of dry air at low pressure which flows in the inner side of the membrane. The performance of the EG process was studied as a function of the membrane manufacturing process as well as process parameters such as transmembrane pressure and dry air flux rate. The results were compared with the results obtained from the osmotic evaporation process and also with hydrophobic membranes provided by Pall-Exekia. Good agreement was obtained between the experimental results and a model which is based on a series of resistances.